Package org.lwjgl.util.xxhash

Class XXHash


  • public class XXHash
extends java.lang.Object
    Native bindings to xxhash.

    xxHash is an extremely fast Hash algorithm, running at RAM speed limits. It also successfully passes all tests from the SMHasher suite.

    • Method Detail

      • XXH32

        public static int XXH32(java.nio.ByteBuffer input,
                        int seed)
        Calculates the 32-bits hash of sequence length bytes stored at memory address input.
        Parameters:
        input - the bytes to hash. The memory between input & input+length must be valid (allocated and read-accessible).
        seed - the seed that can be used to alter the result predictably

      • XXH32_createState

        public static XXH32State XXH32_createState()
        Creates memory for XXH32_state_t. The state must then be initialized using 32_reset before first use.

        LWJGL note: This function simply delegates to the system malloc() function.

      • XXH32_freeState

        public static int XXH32_freeState(XXH32State statePtr)
        Frees the specified XXH32_state_t.
        Parameters:
        statePtr - the state to free

      • XXH32_copyState

        public static void XXH32_copyState(XXH32State dst_state,
                                   XXH32State src_state)

      • XXH32_reset

        public static int XXH32_reset(XXH32State statePtr,
                              int seed)
        Resets the specified XXH32_state_t.
        Parameters:
        statePtr - the XXH32_state_t to reset
        seed - the seed that can be used to alter the hashing result predictably

      • XXH32_update

        public static int XXH32_update(XXH32State statePtr,
                               java.nio.ByteBuffer input)
        These functions generate the xxHash of an input provided in multiple segments. Note that, for small input, they are slower than single-call functions, due to state management. For small input, prefer 32.

        XXH state must first be allocated, using 32_createState.

        Start a new hash by initializing state with a seed, using 32_reset.

        Then, feed the hash state by calling 32_update as many times as necessary. Obviously, input must be allocated and read accessible. The function returns an error code, with 0 meaning OK, and any other value meaning there is an error.

        Finally, a hash value can be produced anytime, by using 32_digest. This function returns the 32-bits hash as an int.

        It's still possible to continue inserting input into the hash state after a digest, and generate some new hashes later on, by calling again 32_digest.

        When done, free XXH state space.

        Parameters:
        statePtr - the XXH32_state_t to use
        input - the bytes to hash. The memory between input & input+length must be valid (allocated and read-accessible).

      • XXH32_digest

        public static int XXH32_digest(XXH32State statePtr)
        Returns the final 32-bits hash of the specified XXH32_state_t.
        Parameters:
        statePtr - the XXH32_state_t to use

      • XXH32_canonicalFromHash

        public static void XXH32_canonicalFromHash(XXH32Canonical dst,
                                           int hash)
        Default result type for XXH functions are primitive unsigned 32 and 64 bits.

        The canonical representation uses human-readable write convention, aka big-endian (large digits first). These functions allow transformation of hash result into and from its canonical format. This way, hash values can be written into a file / memory, and remain comparable on different systems and programs.

        Parameters:
        dst - the destination canonical representation
        hash - the source hash

      • XXH32_hashFromCanonical

        public static int XXH32_hashFromCanonical(XXH32Canonical src)
        Transforms the specified canonical representation to a primitive value.
        Parameters:
        src - the source canonical representation

      • XXH64

        public static long XXH64(java.nio.ByteBuffer input,
                         long seed)
        64-bit version of 32.

        This function runs 2x faster on 64-bits systems, but slower on 32-bits systems.

        Parameters:
        input - the bytes to hash. The memory between input & input+length must be valid (allocated and read-accessible).
        seed - the seed that can be used to alter the result predictably

      • XXH64_freeState

        public static int XXH64_freeState(XXH64State statePtr)
        64-bit version of 32_freeState.
        Parameters:
        statePtr - the state to free

      • XXH64_copyState

        public static void XXH64_copyState(XXH64State dst_state,
                                   XXH64State src_state)

      • XXH64_reset

        public static int XXH64_reset(XXH64State statePtr,
                              long seed)
        64-bit version of 32_reset.
        Parameters:
        statePtr - the XXH64_state_t to reset
        seed - the seed that can be used to alter the hashing result predictably

      • XXH64_update

        public static int XXH64_update(XXH64State statePtr,
                               java.nio.ByteBuffer input)
        64-bit version of 32_update.
        Parameters:
        statePtr - the XXH64_state_t to use
        input - the bytes to hash. The memory between input & input+length must be valid (allocated and read-accessible).

      • XXH64_digest

        public static long XXH64_digest(XXH64State statePtr)
        64-bit version of 32_digest.
        Parameters:
        statePtr - the XXH64_state_t to use

      • XXH64_canonicalFromHash

        public static void XXH64_canonicalFromHash(XXH64Canonical dst,
                                           long hash)
        64-bit version of 32_canonicalFromHash.
        Parameters:
        dst - the destination canonical representation
        hash - the source hash

      • XXH64_hashFromCanonical

        public static long XXH64_hashFromCanonical(XXH64Canonical src)
        64-bit version of 32_hashFromCanonical.
        Parameters:
        src - the source canonical representation